Classifications

F04B9/00—Piston machines or pumps characterised by the driving or driven means to or from their working members

F04B9/02—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical

F04B9/04—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical the means being cams, eccentrics, or pin-and-slot mechanisms

F04B9/045—Piston machines or pumps characterised by the driving or driven means to or from their working members the means being mechanical the means being cams, eccentrics, or pin-and-slot mechanisms the means being eccentrics

F04B49/12—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by varying the length of stroke of the working members

/YLsoN G? KUNG United States Patent 3,372,647 PUMP Nelson G. Kling, Ringwood, NJ., assignor to Techncon Corporation, a corporation of New York Filed July 8, 1966, Ser. No. 563,872 2 Claims. (Cl. 10S- 153) ABSTRACT OF THE DISCLOSURE This invention relates to pumps and more particularly to pumps which are well adapted for pumping small quantities of liquid. While useful for other purposes, the pump to which the present invention relates is especially useful for delivering small quantities of liquid in chromatography systems.

The pump of the present invention has been developed as an improvement over the pump shown in my U.S. Patent No. 3,220,351, dated lNov. 30, 1965, and in certain respects, over the pumps disclosed in my United States patents, No. 3,301,189, dated Jan. 31, 1967 and No. 3,288,079, dated Nov. 29, 1966.

fIn accordance with the present invention, the pump head and a sub-assembly can be removed as a unit from the pump base or frame and wherein the pump head, which comprises a cylinder bore for the pump piston and the valved inlet and outlet, is removably secured to said sub-assembly, which includes the pump piston, by means readily accessible externally of the sub-assembly without unfastening the means which secures the sub-assembly to the pump frame or base. This permits the pump head to be easily removed from the sub-assembly and thereby provide ready access to the sub-assembly for replacing the piston packing and for other repairs which might be necessary.

The above and other features resulting from the improvements according to the present invention will be more fully understood from the following description considered in connection with the accompanying illustrative drawings.

In the drawings:

FIG. 1 is a view partly in side elevation and partly in section showing a pump according to the invention;

FIG. 2 is a vertical sectional view, on a larger scale, of the pump head and part of a companion sub-assembly; and

FIG. 3 shows a modification.

Referring now to the drawings in detail, and first to FIGS. 1 and 2, the pump assembly 10, according to the presently preferred embodiment of the invention, comprises the sub-assembly 12 and the pump head 14. Surbassembly 12 comprises a plate 16 and a spacer-housing 18 for the piston operating plunger 20 to which the piston 22 which operates in the cylindrical bore 24 of the pump head 14 is secured. Piston 22 is formed of sapphire and has a snug sliding lit with the stainless steel wall which defines the cylindrical Wall of said bore. Said piston is secured to plunger by cementing an end portion of the piston in a recess in the end of plunger 20. The end 26 of said housing 18 ts in a recess 28 in the pump frame 30 and abuts the adjacent end 32 of the pump frame in said recess 28. Plate 16 is secured to the end 32 of the pump frame by a plurality of, say three, circumferentially spaced rods 34 each having an inner threaded end portion 36 threaded into a threaded opening 38 in end lCC 32 of the pump frame and further secured by a nut 40 to which Vaccess is available when the bottom `closure 42 of the pump frame is removed. The outer end ,of each rod 34 is provided with -a screw threaded recess 44 to receive a fastening screw 46 for fastening the plate 16 to each companion `rod 34 in abutting relation to the end of said rod.

Sub-assembly 12 `also inc-ludes member 48 having coaxial bores 50 and 52 which are coaxial with the bore 24 in the pump head 14 for the pump piston 22. A sleeve bearing 54 for piston plunger 20 is fitted in bone 52. Member 48 lits tightly within a recess 56 in plate 16 and has an end recess 58 in which is fitted a wedging member 60 for forcing the fluid seals or packings 60 into fluid tight relation with piston 22. A ring ,62 fixed to plunger 20 is provided in position to abut the washer .64 to thereby prevent the spring `66 from forcing plunger 20 and its attached piston 22 out of the member 48 when subassem'bly 12 is detached from the `pump frame 32. In this connection, it will be noted that spring 66 is Va compres.- sion spring, one end of which bears against the plate 68 which abuts the inner side `of plate 1,6, the opposite end of said spring abutting plate 70 which is secured to `the outer end of plunger 20.

It will be understood that the liquid intake stroke of piston 22 is accomplished by the expansion of spring 66, The liquid expelling stroke of piston 22 is effected by the movement of 'the rod 72 `to the left,`viewing xFIG. 1. Rod 72 is mounted for longitudinal movement 'in bearings 74 and 76 carried, respectively, by the end 26 of housing 12 and by stationary member`78 which is mounted in the end of the pump frame 30. A low speed synchronous motor 82 is mounted on the pump frame 30 and is coupled to the piston-plunger operating rod 72 by ,the driving pulley 84 mounted on `the shaft of said motor, timing belt 86 which drives pulley 88, and an eccentric 90 which is fixed to speed reducing pulley 88 and bears against the eccentric follower 92 which is xed to rod 72. Piston 22 is operated at a low speed, for example, but without narrow limitation, twenty-five liquid-expelling strokes per minute.

The fluid intake stroke of piston 22 under the influence of spring 66 is limited by the adjustable stop 94 which is in screw threaded engagement in the stationary member 78. A knob 96 is fixed to the outer end of stop 94 for rotating said stop and thereby moving it towards and away from the confronting end of rod 72. A stationary micro-dial 98 is xed to the end 80 of the pump frame 30 in any suitable way as by bolts 100. Stop 94 can be locked in adjusted position by rotation of member 102 which is in screw threaded engagement with the outer end portion of stop 94, the inner end of member 102 being tapered and in engagement with a slanted end of member 104 of any suitable material such as, for example, nylon, which slidably lits within a cross bore 106 in stop 94. Said member 104 is releasably forcible against the screw threaded portion of member 7-84 when locking member 102 is rot-ated so as to move towards the left, viewing FIG. 1, while vst-op 94 can tbe unlocked for adjustment by knob 96 when member 102 is turned for moving it in the opposite direction. i

The above-mentioned pump head 14 will now be described in detail. Said pump head comprises a stainless steel block 108 which is removably secured on plate 16 by a plurality of releasable fastening members, here shown as clips 110, which engagee the flange 112 of block 108, each of said fastening members being releasably secured to plate 16 externally thereof by a companion Screw 114. A liuid passage 116` is provided in block 108 and has enlarged end portions 118 and 120 which are threaded to receive the threaded inlet and outlet fittings 122 and 124, respectively. Valve seats 126,

which are preferably formed of Teflon are disposed in the enlarged portions 118 and 120 of the iluid passage 116 for the inlet and outlet ball valves 12S and 130, respectively, which are preferably formed of stainless steel. Spacers 132 and 134 rest on valves 128 and 130, respectively, and tit loosely in passage 116 so that liquid can ow freely in passage 116. A slot 136 is provided in the upper ends of spacers 132 and 134 to allow iluid flow in the event that the spacers are forced against the upper shoulders in the uid passage. These spacers serve to ll undesired volume in the iluid passage thereby facilitating bleeding air from block 108 and they also add weight to the valves for improved seating on the companion valve seats 126,

In the form of the invention shown by FIG. 3, the block 108A of the pump head 14A is releasably secured to the sub-assembly 12 by a cap 140 which encloses said block and is attached to plate 16 by screws 142.

While I have shown and described the preferred embodiments of my invention, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that certain changes in the form and arrangement of parts and in the specific manner of practicing the invention may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.

What is claimed is:

1. A positive displacement pump, comprising a main frame assembly including a main frame,

an operating rod disposed for reciprocation within and through said frame,

eccentric motive means coupled to said operating rod for driving said rod;

an intermediate assembly including a housing,

a plunger disposed for reciprocation within said housing and having a piston extending therefrom through said housing,

an annular seal disposed on said piston outside of said housing,

means securing and supporting said intermediate assembly only to said main frame assembly with said plunger coupled to said operating rod by separatable independent engaging surfaces carried by said plunger and rod,

a spring biasing said plunger towards said operating rod for continuous engagement of said independent separatable surfaces;

a pump head assembly including a block having a first passageway therethrough with a valve in each end thereof;

a piston bore in said block communicating with said rst passageway;

means accessible outside said housing of said intermediate assembly for releasing said housing from said main frame with said rod being retained with said frame by the separating of said surfaces, and means accessible from outside of said housing for releasing said pump head assembly from said housing whereby said piston is retained with said housing and said seal is exposed for replacement.

2. A pump according to claim 1 wherein said last releasably securing means includes a flange on said pump head housing and a plurality of members mounted to said intermediate housing and overlying said ange.